(a) Field of the Invention
The present invention relates to connectors, and particularly to an electric connector for the electric connection between a chip module and a circuit board.
(b) Description of the Prior Art
With the improvement of technology, electric connectors of zero insertion force CPU sockets become more and more popular. Prior arts are referring to China patent No. 95223360. The prior art presents an electric connector of a zero insertion force CPU socket, comprising an upper cover, a seat and a retaining spindle. The seat has a plurality of terminal slots inserting correspondingly in the same numbers of the conductive terminals. The retaining spindle is installed in one side of the seat. Besides, the upper cover is slideable with respect to the surface of the seat. The defects of the electric connector of a zero insertion force CPU socket are described as the followings. When the CPU is inserted in an electric connector for operation thereof, the retaining spindle must be pushed so that the upper cover moves towards to far distantance of the joint of the retaining spindle. According to tolerant force analysis, the upper cover receives two different forces. One is the resistance force induced from CPU pins moving towards the opposite direction of the upper cover. The other is the pushing force induced from the joint of the retaining spindle moving towards the same direction of the upper cover. The two different forces exert pressures on the upper cover so that the central part thereof becomes warped. The greater friction is produced between the upper cover and the seat so that larger force is needed when the retaining spindle is pushed downwards. The greater friction causes the operation to be inconvenient. Furthermore, in an extreme situation the two different forces may cause the central part of the CPU raised so as to prevent from the all pins of the CPU in contact with the terminals of the electric connector.
Therefore, it is necessary to develop a novel electric connector to overcome the above-mentioned defects.